Boron Neutron Capture Therapy (BNCT) is conducted by loading boron biochemically into a tumor and irradiating with thermal neutrons. Since the ranges of the alpha particles and lithium ions that result from the capture are very short (mum), the clinical efficacy is only guaranteed if this boron is in a sensitive area of the tumor cell. Several techniques such as alpha track-etch and Secondary Ion Mass Spectrometry (SIMS) have been used to localize boron in individual cells, but neither technique has been totally successful in quantitative localization. Resonance Ionization Spectroscopy (RIS), a new ultra-trace element analysis technique, utilizes precisely tuned lasers to efficiently ionize a chosen element without interference from the overwhelming large background of other constituents in the sample. RIS, when combined with ion sputtering leads to a new analytical technique - Sputter Initiated Resonance Ionization Spectroscopy (SIRIS). It has almost all of the advantages of SIMS, and surpasses it in the following SIMS shortcomings: efficiency, matrix dependence, isobaric and molecular interferences, and sensitivity. We propose to use SIRIS to localize and quantitate the boron concentration in cells at the parts per million (ppm), or sub-ppm level with resolution at micrometer, or smaller dimensions.